Control mechanism for an electrode-clamping assembly in an electric furnace

ABSTRACT

The grip of the holder on an electrode in an electric smelting furnace is controlled by a mechanism which transmits the force generated by a pressure medium to the holder. Mechanical locking means are provided for maintaining the grip of the holder upon relaxation or failure of the pressure medium.

United States Patent Inventor Harald Krogsrud Gjettum, Norway Appl. No. 85,392 Filed Oct. 30, 1970 Patented Jan. 11, 1972 Assignee Elkem A. S.

Elkemuset, Majorstua, Norway Priority Nov. 13, 1969 Norway 4498/69 CONTROL MECHANISM FOR AN ELECTRODE- CLAMPING ASSEMBLY IN AN ELECTRIC Primary Examiner-Bernard A. Gilheany Assistant Examiner-R. N. Envall, Jr. Attorney- Eyre, Mann & Lucas ABSTRACT: The grip of the holder on an electrode in an F NACE gg 2 Drawing Figs electric smelting furnace is controlled by a mechanism which transmits the force generated by a pressure medium to the vase u t t i t t Q -n f 269/24 269/30 269/34 ing the grip of the holder upon relaxation or failure of the Int. Cl H05b 7/12 pressure medium.

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HARALD KROGSRUD III- ; 'VIIIIIIIIIIIIIIIIIIIIIIIII A TTORNE Y5 CONTROL MECHANISM FOR AN ELECTRODE- CLAMPING ASSEMBLY IN AN ELECTRIC FURNACE The electrodes in an electric smelting furnace are usually suspended by a holder assembly which surrounds each electrode. The holder assembly includes one or more clamping members or pressure units which are pressed against the electrode by means of hydraulic, pneumatic or mechanical arrangements to grip the electrode and control its position in the furnace. During operation, the pressure of the holder is relaxed from time to time so that the electrode can slide or be moved relative to the holder.

The holderassembly will in many cases effect the suspension as well as the supply of electric current to the electrode. Auxiliary pressure rings comprising one or more clamps may also be employed in conjunction with an electrode holder. When this is done the weight of the electrode may be divided between the holder and auxiliary pressure ring which is frequently employed for forcing or drawing the electrode down through the holder.

The remote control of a hydraulic or pneumatic pressure medium for generating the force required to press the clamps of the holder and auxiliary pressure ring against the electrode is of advantage but the drawback exists that an inadvertent relaxation or loss of the pressure medium may occur whereupon the electrode may slide down into the furnace and make it necessary to shut the furnace down. A combination of mechanical pressure relieved by the remote control of a fluid pressure medium for controlling the force transmitted to the electrode clamps provides a reliable system but these systems are expensive and require a great deal of space if the arrangement is to compensate for variations in the diameter of the electrode which ordinarily occurs in commercial operations.

In accordance with the present invention these drawbacks have been overcome by means of a control mechanism which comprises a housing having a moveable member therein which transmits the force generated by the selected pressure medium to the electrode clamp which is thereby pressed against the electrode to grip it for controlling the position of the electrode in the furnace. The control mechanism includes mechanical locking means which automatically hold the moveable member in a force-transmitting position to maintain the grip of the clamp on the electrode in the event that there should be a relaxation or loss of the forece generated by the pressure medium.

In the preferred form of control mechanism, the moveable member comprises piston means having an applied forcetransmitting portion connected to the electrode clamp for transmitting the forece applied by the pressure medium to the clamp. The preferred form of mechanical locking means include a wedge system having anchor means which bear against a locking extension connected to the piston means to lock the piston means in force transmitting position upon relaxation or loss of the force generated by the pressure medium. The preferred form of anchor means may be adjusted to each and every force-transmitting position of the piston means to automatically lock the piston means in any given position along its line of travel upon a reduction or failure of the force generated by the pressure medium.

The selected pressure medium for applying the force to the piston means is preferably a hydraulic or pneumatic pressure medium. The automatic transfer of the applied force of the fluid medium to pure mechanical pressure means for maintaining the force on the electrode clamp in accordance with the present invention provides the advantage of reliability coupled with remote control.

These and other advantages and the details of one preferred embodiment of the present invention herein chosen for the purpose of illustration may be readily understood by reference to the accompanying drawings in which:

FIG. 1 is a schematic sectional view which illustrates one form of electrode clamp and the control mechanism of the present invention when employed for controlling the grip of a pressure ring on the electrode, and

FIG. 2 is an enlarged sectional view of the control mechanism of FIG. 1.

In the drawings, three spaced pressure units or clamping members 10 surround the electrode 12 to form a pressure ring. The pressure ring is tightened by means of the control mechanism 14 which decreases the space between flanges 16 positioned at opposite ends of each clamping member. The control mechanism comprises a housing 18 having a bore 20 in which piston means are slidably mounted to transmit an applied force to the pressure ring.

The piston means include a piston 22 having an applied force transmitting portion or rod 24 which extends through an aperture 26 in one end wall of the housing which, in the preferred structure, is mounted to bear against a flange 16 of one clamping member. Rod 24 is extended through an aperture 30 in such flange and connected at 32 to the next adjacent flange of a second clamping member. Rod 24 is preferably extended through an aperture 34 in the second flange and the rod is free to slide relative to both flanges so that a resilient connection may be provided by compressible means such as the spring 36 and the fixed stop 38.

The form of mechanical locking means shown in the drawing comprise a locking extension member 40 on the piston which as shown in the drawings is a wedge-shaped member that extends out away from the side of the piston opposite to that of the applied force-transmitting rod. The piston means and wedge-shaped locking extension are locked in any desired position in the housing by anchor means having a corresponding wedge-shaped surface which bears against the wedgeshaped locking extension. The particular form of anchor means chosen for the purpose of illustration comprise a pair of spaced anchor members 42 mounted in fixed position in housing 18 and a pair of spaced wedges 44, slidably mounted in the space between the locking extension and anchor members. Movement of the wedges 44 relative to the locking extension is preferably effected by means of a piston 46 slidably mounted in a bore 48 in the locking extension. The wedges 44 are connected to piston 46 by means of a yoke 52 and rod 54.

In a preferred operation of the control mechanism, a hydraulic or pneumatic fluid medium under pressure from a suitable source 56 is simultaneously supplied to bore 20 by means of a flexible pipe 58, control valve 60 and inlet port 62 and to bore 48 by means of flexible pipe 64, control valve 66 and inlet port 68. As a result of the force applied to piston 22, the piston and its locking extension move to the right in bore 20 (FIG. 2) and the force applied to the piston is transmitted by rod 24 to the clamping member 10 to tighten the pressure ring and press the clamping members against the electrode. As piston 22 moves to the right, the force applied to piston 46, causes this piston to move left (FIG. 2) and also move the wedges 44 to the left to fill the space between the wedgeshaped locking extension 40 and the spaced anchor members 42. The space between the locking extension and anchor members is automatically and continuously filled. If there should be a relaxation or failure of the force generated by the fluid pressure medium, the mechanical locking means will take over and hold the piston means in a force-transmitting position by virtue of pure mechanical pressure established between the anchor means and the locking extension on piston 22 which prevents the piston means from moving to the left in FIG. 2. The mechanical lock may be relieved by reestablishing the applied force of the fluid pressure medium on piston 22 in bore 20. When the force of the fluid pressure on piston 22 equals that which existed at the time the mechanical lock was established the mechanical pressure between the anchor means and the piston-locking extension will be reduced to zero. In order to move the piston means to the left in FIG. 2, to relax the grip of the pressure ring on the electrode, a force is applied to the left side of piston 46 (FIG. 2) as by means of fluid pressure supplied to bore 48 through valve 66, flexible pipe 72 and inlet port 74. The applied force on piston 46 will move the piston and wedges 44 to the right in FIG. 2 to open a space between the locking means and locking extension and the piston means may be moved to the left to relax the pressure of the clamps 10 against the electrode by reducing the applied force of the fluid medium on piston 22 in bore 20.

In the preferred operation the two pistons are moved simultaneously to maintain the mechanical locking position but this is not necessary and the pistons can be moved independently of each other with a time delay between movement of the pistons if this is desired. Control of the movement of piston 46 may be effected by a combination of a mechanical pressure medium and a fluid pressure medium. In such case a compressible member such as a coil spring (not shown) may be positioned on one side of the piston and a fluid pressure medium may be supplied to the other side of the piston for the automatic control of the movement of piston 46.

The control mechanism of the present invention may be used in connection with electrode holder assemblies as well as pressure rings which usually constitute part of the electrodeslipping device. Some examples of typical electrode holder assemblies and pressure ring slipping devices are described in US. Pat, Nos. 2,668,183, 2,671,816, 2,778,865, 2,845,468, 2,948,765 and 2,949,496. The control mechanism of the present invention for pressing the clamping members against the electrode may be used in place of the control mechanisms described in the aforementioned issued patents and in making the substitution the mechanism may be arranged tangentially as well as radially or at any desired angle in relation to the electrode.

The utility of the mechanical locking means of the present invention is not restricted to the specific piston means illustrated in the drawings and if desired the mechanical locking means may be used with various types of piston means that are employed for applying pressure to the electrode-clamping members.

It will be understood that it is intended to cover all changes and modifications of the preferred embodiment of the invention which do not constitute a departure from the spirit and scope of the invention.

What is claimed is:

l. A control mechanism for an electrode-clamping member in an electrode furnace which comprises a housing, piston means in said housing for transmitting an applied force to said electrode-clamping member, means for applying a force to said piston means and mechanical locking means for holding said piston means in a force-transmitting position upon relaxation of the force applied thereto.

2. The structure specified in claim 1 in which the mechanical locking means include a locking member connected to said piston means and anchor means for holding said extension and piston means in a force-transmitting position upon relaxation of the force applied to said piston means.

3. The structure specified in claim 1 in which the mechanical locking means include a wedge-shaped member connected to said piston means and anchor means having a corresponding wedge-shaped surface which bears against said wedgeshaped member to apply mechanical pressure for holding said piston means in a force transmitting position upon relaxation of the force applied to said piston means.

4. A control mechanism for an electrode clamping member in an electric furnace comprising a housing, a piston slidably mounted in said housing having an applied force-transmitting member connected to said clamping member, means for applying a force to said piston, a locking member connected to said piston and anchor means for applying pressure to said locking member for holding the piston in a force-transmitting position upon relaxation of the applied force.

5. The structure specified in claim 4 in which the means for applying force to said piston comprise at least one inlet port in said housing for subjecting the piston to a force applied by a fluid pressure medium.

6. The structure specified in claim 4 in which the means for applying force to said piston comprise an inlet port in said housing for supplying a fluid pressure medium which subjects the piston to an applied force, and in which the locking member and anchor means have corresponding wedge-shaped surfaces which bear against each other to establish mechanical pressure for holding the piston in a force-transmitting position upon relaxation of the force of said fluid pressure.

7. A control mechanism for an electrode clamping assembly in an electric furnace which comprises a housing, a moveable member in said housing connected to said clamping assembly for transmitting an applied force for gripping the electrode, fluid means for applying a force to said moveable member, said moveable member having a wedge-shaped locking extension thereon and anchor means having a corresponding wedge-shaped surface which bears against said extension to establish mechanical pressure for holding the moveable member in a force-transmitting position upon relaxation of said force.

8. The structure specified in claim 7 in which the anchor means include a spaced pair of anchor members and a pair of spaced wedges slidably mounted to bear against said anchor members and wedge-shaped extension, and means for moving said wedges to maintain a bearing engagement with said anchor members and wedge-shaped locking extension to apply mechanical pressure to said wedge-shaped member to hold said moveable member in a force-transmitting position throughout the line of travel of said moveable member upon relaxation of said force.

9. The structure specified in claim 8 in which the means for moving said spaced wedges include a piston connected to said wedges and means for subjecting the piston to a fluid pressure medium to move the piston and spaced wedges.

10. The structure specified in claim 9 in which the wedgeshaped locking extension has a bore therein in which the piston for moving said wedges is slidably mounted.

11. A control mechanism for an electrode clamping assembly in an electric furnace which comprises a housing, a piston slidably mounted therein having an applied force-transmitting member connected to said electrode clamping assembly, fluid pressure means for applying a force to said piston, a wedge-shaped locking extension connected to said piston, a pair of spaced anchor members, a pair of spaced wedges slidably mounted to bear against said anchor members and against said wedge-shaped locking extension, piston means activated by a fluid pressure medium for moving said pair of wedges to maintain a bearing engagement with said anchor members and said wedge-shaped locking extension to apply mechanical pressure to said wedge-shaped locking extension to hold said force-transmitting means in a force-transmitting position upon relaxation of said force.

12. The structure specified in claim 11 in which the piston means comprise a piston slidably mounted in a bore in said wedge-shaped locking extension, said piston being connected to said wedges to control the movement thereof.

13. The method of transmitting force to at least one clamp- I ing member to press it against the electrode in an electric furnace by means of a first moveable member which transmits the force applied by a fluid pressure medium to the clamping member and a second moveable member which transmits mechanical pressure to said first moveable member upon relaxation of said applied force which comprises the steps of supplying a fluid pressure medium to said first member to generate an applied force thereon to move said first member in one direction into a force-transmitting position and moving said second member in one direction into position to engage said first member for transmitting mechanical pressure to said first member to hold it in a force-transmitting position upon relaxation of said applied force.

14. The method specified in claim 13 which includes the step of moving said first and second members simultaneously.

15. The method specified in claim 13 which includes the step of moving said second member in a second direction to disengage it from said first member and relaxing the force applied to said first member to move it in a second direction to engage said second member.

Inventork s) Q Harald Krogs'rud UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTKUN Patent No. 3 3 'a 5 9 v Dated J n y 97 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 1, Lite 43: "forece" should read -'-force-- Col. 1, Line 48: "foreoe" should read "force- Col. 3, Line 38 (Claim 1): "electrode furhace" shouid read --e1ectric furnace- I Signed andsealed this 15th day of August 1972.

(SEAL) Attest;

EDWARD M. FLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents OHM powso (169) USCOMM-DC scan-boa U.S. GOVERNMENT PRINTING OFFICE: l9, 0-3553.

UNITED STATES PATENT OFFICE CERTIFICATE OF CQRRECTKQN Patent No. v 3 5 H 5 9 Dated January 11, 1972 Inventor s) Hare 1d Krogs'rud It is certified that errot appears in the above-identified patent and that. said Letters Patent are hereby corrected as shown below:

Col. 1, Lite 5: "forece" should read -foicce-- C01. 1, Line 48: "forage" should read "force-- 3, Line 38 (Claim 1): "electrode furnace" should read "electric furnace- Signed and sealed this 15th day of August 1972.

(SEAL) Attest:

ROBERT GOTTSCHALK EDWARD M. FLETCHER, JR. Attesting Officer Commissioner of ?atents FORM P0405) (10459) uscoMM-Dc 60375-569 U-S. GOVERNMENT PRINTING OFFICE! 1989 0"355'334 

1. A control mechanism for an electrode-clamping member in an electrode furnace which comprises a housing, piston means in said housing for transmitting an applied force to said electrodeclamping member, means for applying a force to said piston means and mechanical locking means for holding said piston means in a force-transmitting position upon relaxation of the force applied thereto.
 2. The structure specified in claim 1 in which the mechanical locking means include a locking member connected to said piston means and anchor means for holding said extension and piston means in a force-transmitting position upon relaxation of the force applied to said piston means.
 3. The structure specified in Claim 1 in which the mechanical locking means include a wedge-shaped member connected to said piston means and anchor means having a corresponding wedge-shaped surface which bears against said wedge-shaped member to apply mechanical pressure for holding said piston means in a force transmitting position upon relaxation of the force applied to said piston means.
 4. A control mechanism for an electrode clamping member in an electric furnace comprising a housing, a piston slidably mounted in said housing having an applied force-transmitting member connected to said clamping member, means for applying a force to said piston, a locking member connected to said piston and anchor means for applying pressure to said locking member for holding the piston in a force-transmitting position upon relaxation of the applied force.
 5. The structure specified in claim 4 in which the means for applying force to said piston comprise at least one inlet port in said housing for subjecting the piston to a force applied by a fluid pressure medium.
 6. The structure specified in claim 4 in which the means for applying force to said piston comprise an inlet port in said housing for supplying a fluid pressure medium which subjects the piston to an applied force, and in which the locking member and anchor means have corresponding wedge-shaped surfaces which bear against each other to establish mechanical pressure for holding the piston in a force-transmitting position upon relaxation of the force of said fluid pressure.
 7. A control mechanism for an electrode clamping assembly in an electric furnace which comprises a housing, a moveable member in said housing connected to said clamping assembly for transmitting an applied force for gripping the electrode, fluid means for applying a force to said moveable member, said moveable member having a wedge-shaped locking extension thereon and anchor means having a corresponding wedge-shaped surface which bears against said extension to establish mechanical pressure for holding the moveable member in a force-transmitting position upon relaxation of said force.
 8. The structure specified in claim 7 in which the anchor means include a spaced pair of anchor members and a pair of spaced wedges slidably mounted to bear against said anchor members and wedge-shaped extension, and means for moving said wedges to maintain a bearing engagement with said anchor members and wedge-shaped locking extension to apply mechanical pressure to said wedge-shaped member to hold said moveable member in a force-transmitting position throughout the line of travel of said moveable member upon relaxation of said force.
 9. The structure specified in claim 8 in which the means for moving said spaced wedges include a piston connected to said wedges and means for subjecting the piston to a fluid pressure medium to move the piston and spaced wedges.
 10. The structure specified in claim 9 in which the wedge-shaped locking extension has a bore therein in which the piston for moving said wedges is slidably mounted.
 11. A control mechanism for an electrode clamping assembly in an electric furnace which comprises a housing, a piston slidably mounted therein having an applied force-transmitting member connected to said electrode clamping assembly, fluid pressure means for applying a force to said piston, a wedge-shaped locking extension connected to said piston, a pair of spaced anchor members, a pair of spaced wedges slidably mounted to bear against said anchor members and against said wedge-shaped locking extension, piston means activated by a fluid pressure medium for moving said pair of wedges to maintain a bearing engagement with said anchor members and said wedge-shaped locking extension to apply mechanical pressure to said wedge-shaped locking extension to hold said force-transmitting means in a force-transmitting position upon relaxation of said force.
 12. The structure specified in claim 11 in which the piston means comprise a piston slidably mounted in a bore in said wedGe-shaped locking extension, said piston being connected to said wedges to control the movement thereof.
 13. The method of transmitting force to at least one clamping member to press it against the electrode in an electric furnace by means of a first moveable member which transmits the force applied by a fluid pressure medium to the clamping member and a second moveable member which transmits mechanical pressure to said first moveable member upon relaxation of said applied force which comprises the steps of supplying a fluid pressure medium to said first member to generate an applied force thereon to move said first member in one direction into a force-transmitting position and moving said second member in one direction into position to engage said first member for transmitting mechanical pressure to said first member to hold it in a force-transmitting position upon relaxation of said applied force.
 14. The method specified in claim 13 which includes the step of moving said first and second members simultaneously.
 15. The method specified in claim 13 which includes the step of moving said second member in a second direction to disengage it from said first member and relaxing the force applied to said first member to move it in a second direction to engage said second member. 